Down conversion mixers used in many radio frequency (RF) communication devices may be passive or active. Active mixers may provide conversion gains typically more than zero dB, while passive mixers may provide conversion gains less than zero dB. Passive mixers, however, may have a number of advantages over active mixers. For example, passive mixers may consume less power, have lower noise figure, and cause less distortion, as compared to the active mixers. The lower noise figure in passive mixers is due to nonexistence of flicker noise, which is the main cause of the higher noise figure in active mixers.
Many down conversion mixers used in wireless communication systems include passive mixers, including multiphase mixers, which may be utilized in, for example, over-sampling passive mixers, where multiple local oscillator (LO) signals with the same frequency but phase shifted with respect to each other (e.g., non-overlapping clocks) may be used in conjunction with an appropriate switching network. Multi-phase, non-overlapping clock signals may be required for a variety of passive-mixer-based circuits. Current non-overlapping clock generation schemes may suffer from a number of limitations, including low frequency of operation, uncertain startup behavior, difficulty in mode selection, and flicker noise coupling (e.g., when used to drive single-ended passive mixers). Therefore, the need exists for a non-overlapping clock generation technique that can significantly mitigate these problems.